Once the green light comes on, you are charged. The other light is sort of orangy red, so hopefully nothing is wrong with the unit and it is just showing a discharged battery, not fault.

I wouldn' velcro the FS4 to the battery. It would problably throw the balance of the camera off, plus be a pain to get at the battery to change it. I took some pictures of how I velcro mine to the back accessory plate of the camera.
www.blueoceanfilms.com/fs4

Thanks Rob for the tip and the pictures of your set-up. That's actually what I was meaning to say. To the plate. When I mentioned battery, I was meaning the battery on the FS.

I still haven't had a chance to check out the unit except to charge the batteries. Can't wait. Boy, I've seen some real negative postings on other thread(s) about the unit just the other day. But I'm not going to let myself get all caught up in it. I'm going to think positive about my purchase :)